Have you tried uninstalling it, even deliberately damaging it by removing the parent folder, or even deleting regedit trees if you know what you're doing, then re-install it. The installer seems to be able to handle a lot of user abuse and self repair. If you need a DVD of the media most PC shops will happily offer you one (maybe for a very small fee or thrown in if for free if you buy something else), but they won't supply the license key if they are legit.
For what it's worth, even Office 97 works beautifully on Windows 10.
Thank you, I have a paid Office 2009 running on 32 bit XP on an unconnected PC that still meets all my needs. There's hope!!!
We use Office365 (which we call Office364 because their cloud crashes once a year) at work and it's the pits. It's slow to load, it's missing important features of the local client and it has a stupid security model inside the cloud framework. Absolutely hate it.